In the last few decades, use of energy storage systems for ensuring an optimum utilization of energy in machines has gained widespread popularity. Such energy storage systems may store energy in one or more rotating flywheels that are being accelerated or decelerated by a connected motor or a generator. The stored energy may then be utilized for operating a machine in a cost-effective manner.
However, in case of over-speeding of an engine, the flywheels that are made of steel may break into large ballistic pieces. In order to mitigate this problem, regulatory authorities, such as the Society of Automotive Engineers (SAE) have established certain qualification standards of survival for a flywheel. For example, a flywheel is considered fit to be used in the machines only if the flywheel may operate at 2.5 times a rated rotational speed. However, in order to operate at 2.5 times the rated rotational speed, the flywheel has to be designed to withstand 6.25 times a normal design stress, considering that the stress in the flywheel increases in proportion to the square of the rotational speed of the flywheel. Such limitations hamper designing and manufacturing of the flywheels and therefore affect the energy storing capabilities of the flywheels.